This invention relates to a method for scanning a color fiber optic tube.
FIGS. 1 and 2 show one example of a color fiber optic tube (called FOT hereinafter) 1, which is provided with a substantially rectangular fiber optic plate (called FOP hereinafter) 2 at the front end of th FOT 1. A singal electron gun 3 is connected to the rear end of the FOT 1 for generating electron beam 4 and a plurality of fluorescent screens 5 each comprising an illuminant color material are laminated on the inner suface, facing the electron gun 3, of the FOP 2. On the fluorescent screens 5, for example as shown in FIGS. 2A and 2B, are applied in a band-like form phosphors 5R, 5G and 5B provided with fluorescent characteristics of red color (R), green color (G) and blue color (B), respectively. Information regarding the respective colors of the phosphors 5R, 5G and 5B is sensed through the FOP 2 on a color photo-sensitive material 6 for recording the same which colsely adheres to the FOP 2 and moves upward, for example.
A driving method for the FOT 1 mentioned above, will be described hereunder in connection with a color picture signal PS for a raster scanning type display. Electron beam 4 from the electron gun 3 is scanned so as to synchronize the red, green and blue phosphors 5R, 5G and 5B formed on the rear surface of the FOP 2 with deflection signals of input picture signals, and when the beam 4 passes the fluorescent screens 5, picture signals SR, SG and SB corresponding respectively to the phosphors 5R, 5G and 5B are selected and luminance modulation is carrier out with a selected picture signal PS. In detail, with reference to FIG. 3, during the time interval t0-t1 when the electron beam 4 scans the red hosphor 5R, the picture signal SR representing the red color component is selected and modulated into an electric current of the electron beam thereby to illuminate the red phosphor 5R thereby to make sensitive the color sensitive material 6. In the like manner, during the time intervals t1-t2 and t2-t3 when the electron beam 4 scans the green and blue phosphors 5G and 5B, the picture signals SG and SB respectively representing the green and blue color components are selected and modulated. Accordingly, the picture signals SR, SG and SB are recorded in time series on the photo-sensitive material 6, the picture signal PS represents the picture signal SR, SG or SB which is selectively composed in synchronism with the scanning position of the electron beam 4 and the luminance modulation in the FOT 1 can be realized by the picture signal PS.
The principle for carrying out color recording operation in use of the FOT 1 of the type mentioned above will be described hereunder in conjuction with FIGS. 4 through 6.
FIG. 4 shows a still color picture 1OA displayed on a color cathode ray tube (CRT) of a raster scanning type, and a rectangular part 1OB of the color picture 1OA is subjected to the sampling operation in accordance with the raster scanning method and displayed on the FOP 2 of the FOT 1 as shown in FIG. 5. The picture displayed on the FOP 2 is color separated, in band-shape, into three colors of red, green and blue, and the luminance thereof is modulated with picture signals SR, SG and SB of the separated colors corresponding to the phosphors 5R, 5G and 5B, respectively. The still color picture 10A is sequentially displayed by a portion of the part 10B thereof while shifting the necessary picture elements to a predetermined direction 11 on the red, green and blue phosphors 5R, 5G and 5B formed in a band-shape on the FOP 2 as shown in an electric light display board. In this manner, the picture which is displayed on the FOP 2 of the FOT 1 and moves thereon is sensed on the color photo-sensitive material 6 which adheres closely to the front surface of the FOP 2 and moves at the same speed as that of the displayed picture in the predetermined direction 11. Accordingly, in the case where the electron beam 4 crosses the red phosphor 5R to carry out the luminance modulation, information regarding only the red color in the input pictures signal is recorded as a latent image in the color photo-sensitive material 6. In the same manner, informations regarding the green and blue colors are color-separated and exposed in a band shape to the color photo-sensitive material 6. Thus, one sheet of the completed color latent image picture is exposed to the color sensitive material 6 by moving the sensitive material in synchronism with the display picture and recording them in an overlapping manner.
However, the color photo-sensitive material 6 of the type descrobed above has sensitivity characteristics having difference based on the respective colors R, G and B and based on the output picture element positions. Moreover, a high quality picture output cannot be obtained by the method that the beams are irradiated at the illuminating positions of the respective phosphors under the same conditions.
Furthermore, in the scanning method of the FOP 1 of the type described abive, since the picture signal is separated with respect to the respective color picture elements to illuminate the phosphors, data regarding colors R, G and B, of one picture element are decomposed in the horizontal direction and outputted when the horizontal deviation is continuously carried out, thus making a problem regarding unevenness of the picture. In addition, each phosphor has a flat plate constructure, so that when the electron beam is subjected to the horizontal deviation at a constant speed with respect to the position of the phosphor, the deviation speed is undesirably increased at both ends of the phosphor, thus degrading the quality of the picture.